ArcFuels Supplemental Material: GIS 9.x Tips and Tricks

Transcription

1 ArcFuels Supplemental Material: GIS 9.x Tips and Tricks Supplemental material: GIS Tips and Tricks... 1 Shapefiles: Points, Lines, and Polygons... 2 Creating a New Shapefile (point, line, or polygon)... 2 Editing Shapefiles: Create Polygons in a Shapefile (by digitizing)... 6 Editing Shapefiles: Creating Polygons in a Shapefile (by copying from another polygon shapefile)... 8 Editing Shapefiles: Modify Polygon Shapes... 9 Editing Shapefiles: Adding a Field... 9 Editing Shapefiles: Editing Attributes for a Shapefile Converting from Polygons to Raster Format: Conversion Tool Converting from Polygons to Raster Format: Spatial Analyst Raster Data Cell Size Resample Cell Size Raster Projections Raster File Types and File Naming Extract By Mask Converting Between Integer and Float Rasters Seaming Together two or More Pieces of Raster Data (Mosaic) Ensuring that Zero is the NoData Value & Making Zero the NoData Value Spatial Analyst Creating a New Raster Using the Raster Calculator within Spatial Analyst Building a Difference Raster Using the Raster Calculator Summarizing Data Reclassify Combine Summarizing Data: Calculate Acres Zonal Statistics Post-Processing: Joining Attribute Tables of Raster Data Exporting ArcGIS Data to Google Earth Updated

2 Shapefiles: Points, Lines, and Polygons Creating a New Shapefile (point, line, or polygon) In ArcCatalog, select a folder in the Catalog tree. Click the File menu, point to New Shapefile Alternatively, right click anywhere within the contents window. Point to New Shapefile

3 Type a name for the new shapefile. Click the Feature Type drop-down arrow and select the type of geometry the shapefile will contain. If you eventually want to calculate an area, select a polygon. Click Edit to define the shapefile's coordinate system

4 There are several methods to create the spatial reference. The easiest way is to click the Import button and navigate to a file which has the desired coordinate system. You can use the coordinate system information from any file type: coverages, rasters, or feature datasets and feature classes in a geodatabase.

5 After finding a file with a desired coordinate system, select OK. Add your new shapefile to your ArcMap table of contents. If the Editor toolbar is not visible, right-click anywhere on the toolbar and select Editor.

6 Editing Shapefiles: Create Polygons in a Shapefile (by digitizing) 1 Begin editing by selecting, Start Editing from the Editor drop down menu. There are many components to editing. Please read the Editor toolbar documentation in ArcGIS Desktop Help for more information about all the editing options that are available. The next few steps will focus on creating a simple shapefile and converting this shapefile to a raster. Make sure the Task is Create New Feature and the Target is the shapefile you just created. Use the dropdown menus to change the task or target. Select the sketch tool (pencil) and draw a shape by left clicking with the mouse. Each left-click will result in a point, known as a vertex. Segments are the lines that connect each vertex. 1 Bridget Naylor, USDA Forest Service, PNW Research Station, La Grande Lab, bnaylor@fs.fed.us, contributed to the Editing Shapefiles sections.

7 While drawing, you can undo added vertices by selecting Edit Undo Add Vertex Finish the sketch by double-clicking on the starting point or right-clicking and selecting Finish Sketch. Be sure to save your edits when done by selecting Save Edits from the Editor drop down menu. Note that since our new shapefile is a polygon, you can only save a completed polygon. If you try to save several vertices, your work will be lost. When finished, select Stop Editing from the Editor drop down menu.

8 Editing tips: To delete a single vertex from a sketch, center the pointer over the vertex until the pointer changes. Right-click, then click Delete Vertex. To delete the entire sketch of the feature you are creating, position the pointer over any part of the sketch, right-click, and click Delete Sketch, or press Ctrl + Delete. To finish a sketch, you can double-click the last vertex of the feature or press F2. You can add an additional shape of a line or polygon feature to the sketch by right-clicking over the feature with the Sketch tool and clicking Replace Sketch. Editing Shapefiles: Creating Polygons in a Shapefile (by copying from another polygon shapefile) In ArcMap, add a new empty shapefile to the table of contents. Select Editor and click Start Editing from the Editor toolbar. Click the Target layer drop-down arrow and click the layer to which you want the copied feature to belong. Click the Edit tool. Editing tips: Click the feature you want to copy. Hold down the Shift key while clicking features to select additional features. Click the Copy button on the ArcMap Standard toolbar. Click the Paste button on the ArcMap Standard toolbar. The feature is pasted on top of the original feature. Using Cut and Paste (rather than Copy and Paste) will only transfer geometry. Attributes are not pasted, even if the source and target layers are the same or have identical schema. The appropriate geodatabase behavior and default or null values will be populated in the target layer If attributes are not copied, you can copy and paste the individual attributes or use the Attribute Transfer tool on the Spatial Adjustment toolbar to pass along the existing attribute values to the new features

9 Editing Shapefiles: Modify Polygon Shapes In ArcMap, add a shapefile to the table of contents. Select Editor and click Start Editing from the Editor toolbar. Click the Target layer drop-down arrow and click the layer to which you want to edit. Click the Current Task drop-down arrow and click Reshape Feature. Click the Edit tool. Click the feature you want to reshape. Click the tool palette drop-down arrow and click the Sketch tool. Create a line according to the way you want the feature reshaped. Right-click anywhere on the map and click Finish Sketch. The feature is reshaped.. Editing Shapefiles: Adding a Field With the attribute table open on the file of interest (can be raster or polygon), select Options, then Add New Field.

10 Name the file and Select a Type. For numeric fields: use Float or Double if decimal points are important; use Long or Short Integers if decimal points are not important. For text fields: use text and enter the length (or number of characters needed). You will not be able to enter text that contains more characters than the length. Leave the Precision and Scale set at 0. Proceed to the next section to learn how to populate this new field. Editing Shapefiles: Editing Attributes for a Shapefile The Attributes dialog box allows you to view and edit attributes of features you have selected in your map when you are in an edit session. You can open it by clicking the Attributes button on the Editor toolbar.

11 The left side of the dialog box lists the features you have selected. Features are listed by their primary display field and grouped by layer name. The number of features selected is displayed at the bottom of the dialog box. The right side of the Attributes dialog box contains two columns: the attribute fields of the layer you are viewing, and the values of those attribute properties. The attribute fields, such as ZONING and PARCEL_ID, are listed under the Property column, and their values are in the Value column. o o o o o Click the Editor menu and click Start Editing. Click the Edit tool on the Editor toolbar. Select the features whose attributes you want to edit. Click the Attributes button on the Editor toolbar. Click the feature on the left side of the dialog box. The attribute values that appear on the right side of the dialog box depend on what you click on in the tree on the left side of the dialog box. The layer's attribute properties appear on the right side of the dialog box, and the feature flashes on the map. o o o Click in the Value column on the right side and type the attribute value. Press Enter. Click the Close button to close the dialog box. Editing tips: You can change the primary display field for a layer on the Fields tab of the Layer Properties dialog box. To open the dialog box, right-click the layer name in the table of contents. To add attributes to all selected features in a layer, click the layer name, click in the Value column, type the attribute value, then press Enter. To flash a feature on the map, click the primary field on the left side of the dialog box; to zoom to the feature, right-click and click Zoom To. Double-click a layer name to see the primary display fields representing the selected features in the layer. Double-click again to hide the primary display fields. To remove features from the selection, right-click the primary display field on the left side of the dialog box and click Unselect. To delete an attribute value, right-click over the value and click Delete. You can also press the Delete key. To undo edits, click the Undo button on the ArcMap Standard toolbar. You can use attribute domains to create a list of valid attribute values for a feature in a geodatabase. You can also view and edit attributes using the table window.

12 When editing attributes, you can perform calculations using the field calculator in the table window. You can also view and edit attributes using the table window. You can also edit attributes in the table window. An attribute table window can show you the values for all features in a layer, not just those selected. Editing attributes through the table window allows you to quickly make changes to several features (records) at once using the Field Calculator. In addition, the table window allows you to add and delete fields and customize how the fields appear by setting up field aliases, hiding fields, and so on. o o o o Click Editor on the Editor toolbar and click Start Editing. Open the table. Click the cell containing the attribute value you want to change. Type the values and press Enter. The table is updated. If you need to make the same edit to numerous rows, select all of the rows which you are interested in changing to the same value (they will be blue). Then, right-click on the field which will be modified and select Field Calculator. Ignore the error message by clicking Yes (this error message will only appear if you are not currently in an Edit Session). Type the changed value into the Field Calculator and click OK. Converting from Polygons to Raster Format: Conversion Tool

13 Open ArcToolbox, if not already open. Navigate to: Conversion Tools To Raster Polygon to Raster

14 Alternatively, within ArcToolbox, select the Index tab. Then type polygon in the keyword search box. Select: Polygon to Raster (conversion) When the tool opens, select the shapefile you want to convert to a raster from the Input features drop down menu or navigate to the desired shapefile using the browse button. The Value field selected here will become the Value in the output raster. If you are creating a raster of treatment units, you would likely want the Value field to be the unit ID number. Name the Output Raster Dataset with no file extension. See previous section on file types and naming for more information.

15 Change the Cell Size to match the size of the other raster data sets you are working with. If you plan to use this newly created raster to perform further analysis, comparisons, etc. with any other raster data, you will need to ensure everything is aligned. See the Spatial Analyst section of this GIS Appendix below for a visual depiction of raster alignment. You can ensure that all of your data are aligned by modifying the Environments settings. NOTE: Explore the Cell Assignment option if you are not happy with the produced output raster. Cell Assignment will determine how a value is assigned to a cell if more than one feature falls within a cell. NOTE: The Priority field option is used when there are overlapping polygons within your shapefile. After clicking Environments, Expand the General Settings.

16 Scroll downward to the Snap Raster drop down list. Select one of your existing rasters as the Snap Raster. This ensures that your data are properly aligned. Click OK to return to the Polygon to Raster tool and OK to initiate the tool.

17 Converting from Polygons to Raster Format: Spatial Analyst This similar process, only with fewer processing options, can be accomplished through a tool accessed through the Spatial Analyst Toolbar. If the Spatial Analyst toolbar is not visible, right-click anywhere in the toolbar and select Spatial Analyst. Before proceeding further, you need to set up your Spatial Analyst options. See the Spatial Analyst section below to learn how to set up the options. From the Spatial Analyst dropdown menu, select Convert Features to Raster

18 Click the Input features drop-down arrow and select the feature layer you want to convert to raster. Alternatively, click the browse button to navigate to the location of a feature dataset. The Field selected here will become the Value in the output raster. If you are creating a raster of treatment units, you would likely want the Field to be the unit ID number. Change the Cell Size to match the size of the other raster data sets you are working with. Name the Output Raster Dataset with no file extension. See previous section on file types and naming for more information. Click OK. NOTE: If any features are selected in the layer you choose as the input, only those selected features will be converted. Raster Data A raster, also known as a grid, consists of a matrix of cells (or pixels) organized into rows and columns where each cell contains a value representing information, such as fuel model, elevation, etc. Rasters are digital aerial photographs, imagery from satellites, digital pictures, or even scanned maps. Rasters contain either discrete (e.g., fuel model) or continuous information (e.g., elevation) or are simply pictures (ESRI 2009). When adding raster data to your ArcMap table of contents, you may be prompted to build pyramids. It does not really matter if you choose Yes or No; however selecting Yes will speed up viewing the data at varying scales.

19 Cell Size To determine the cell size, right click on your raster in the table of contents and select Properties. Go to the Source tab and view the Cellsize (X,Y). In this example, cell size is 30 m x 30 m or 900 m 2. If the cell size of one or more of your raster datasets is unlike the others, you will need to Resample. Resample Cell Size If the cell size of one or more of your raster datasets is unlike the others, you will need to use the Resample geoprocessing tool. Realize that when you resample, you cannot gain any more detail in your

20 dataset; consider resampling the raster with the smaller cell size (which has more detail) to the larger cell size. Open ArcToolbox if not already open. Navigate to: Data Management Tools Raster Raster Processing Select: Resample

21 Alternatively, within ArcToolbox, select the Index tab. Then type resample in the keyword search box. Select: Resample (management) When the tool opens, select the raster to resample from the drop down list. Name the output raster (with no extension; see raster file types above). Type in the desired output file size and then click Ok. Note that in this scenario Resampling Technique can be left as the default. Consider the other options if you plan to drastically change cell size.

22 Raster Projections Before beginning a project, it is important to ensure that all of your raster data and dataframe are in the same projection. Some processes may function properly with varying projections, but others will not, so it is best to eliminate a projection issue as a potential source of error later in your analysis. The projection of your dataframe is established when the first file is added to the table of contents, but can be changed at any time. To determine the projection of your dataframe, right click on the Layers icon in the table of contents and select Properties.

23 Select the Coordinate System tab and view the dataframe s current coordinate system. The coordinate system of the dataframe is established when the first file is added to the table of contents. There are several methods to change the coordinate system of the dataframe. The easiest way is to click the Import button and navigate to a file which has the desired coordinate system.

24 To determine the projection of your data, right click on your raster in the table of contents and select Properties. Select the Source tab and scroll down to Spatial Reference. To change the projection, you will need to follow the next few steps.

25 Open ArcToolbox if not already open. Navigate to: Data Management Tools Projections and Transformations Select: Project Raster NOTE: There is a difference between the Project Raster and Define Projection tools. Define Projection is used when there is no projection associated with your data. Project Raster is used when there is a projection, but you would like to change it. Alternatively, within ArcToolbox, select the Index tab. Then type project in the keyword search box. Select: Project Raster (management)

26 When the tool opens, select the raster you would like to change the projection of from the drop down list. Name the output raster (with no output extension; see naming raster file types below). Select a new projection using. There are several methods to change the spatial reference. The easiest way is to click the Import button and navigate to a file which has the desired coordinate system. You can use the coordinate system information from any file type: coverages, rasters, or feature datasets or feature classes in a geodatabase.

27 After finding a file with a desired coordinate system, select OK. Depending on the output coordinate system chosen, you may have to select a geographic transformation. Choose the transformation that is most appropriate for your geographic location. When in doubt, choose NADCON. NADCON is the federal standard for transformations within the continental Unites States. Select OK.

28 Raster File Types and File Naming All raster file types have the same icon in ArcCatalog. The file types a fuels planner will likely see and/or work with most are: ASCII rasters, ESRI rasters, and ERDAS Imagine rasters. ASCII Raster file extension.asc (e.g., fuel_mdl.asc). ASCII file types are exported from fire behavior programs such as FlamMap and FARSITE and need to be converted to ESRI rasters (see below) before they can be viewed. ASCII raster names do not have a character limit, but it is good practice to keep names under 13 characters, as they will need to be shortened when converted to an ESRI raster. If you are working with ArcMap and ArcCatalog version 9.2, you can tell if a file is an ASCII file type by previewing it in ArcCatalog or adding it to the ArcMap table of contents. It will be solid grey in color. When previewed in ArcCatalog, ASCII files are solid grey in color. ERDAS Imagine file extension.img (e.g., fuel_model.img). Imagine file types can be produced using the program ERDAS imagine (program burn severity data is often manipulated with). Fuels planners will likely not need to work with.img rasters. However, since it is the default output file type for many geoprocessing tools within ArcToolbox, it is important to be aware of this file type so that you erase the.img before naming your ESRI raster files.

29 Geoprocessing tool showing default.img in file name. ESRI Raster no file extension (e.g., fuel_mdl). ESRI girds are the typical file format used, native to ArcMap. ESRI rasters have a 13 character file name limit. There are two types of ESRI rasters, Integer and Float. Integer- Discrete attributes for an integer raster are stored in an attribute table. Integer rasters can store only whole numbers, therefore all decimal points are rounded up or down when data are converted to an Integer. Summarizing data for NEPA, for example, can be achieved by exporting the attribute table of an integer raster to Excel. Float- The cells in this type of raster do not fall neatly into discrete categories and therefore do not have an attribute table, the data are continuous. Float rasters can store numbers with decimal points. Burn probability is inherently a float raster because it is expressed as a fraction of 1 and therefore requires storage of decimal points, but can be converted to an integer for easy analysis by multiplying the raster by 1000 (using the Raster Calculator) or reclassifying the raster into new categories. See the Spatial Analyst and Reclassify sections for more detail on this topic. Determine whether or not the file you are working with contains Integer or Float data by right-clicking on the file. If Open Attribute Table is not grayed out, you have integer data. If the Open Attribute Table is grayed out, you have float data.

30 This ESRI raster contains float data because there is no attribute table available to view when right-clicking on the file. In ArcMap and ArcCatalog version 9.3, the ASCII file extensions are visible; therefore you can tell what file type you are working with without previewing the data. This may not be the case with ArcMap and ArcCatalog version 9.2. If you do not see the.asc extension on your ASCII file types in ArcCatalog, go to Tools and select Options. When the window pops up, select the File Types tab. Select New Type. Enter the file extension.asc and type ASCII as the Description of Type. Tools Options File Types New Type

31 Type asc into the File extension. Type ASCII as the Description of Type. Extract By Mask Extracting by mask is a way to clip raster data to a desired shape. Open ArcToolbox if not already open.

32 Navigate to: Spatial Analyst Tools Extraction Select: Extract by Mask

33 Alternatively, within ArcToolbox, select the Index tab. Then type extract in the keyword search box. Select: Extract By Mask (sa) When the tool opens, select the raster layer you would like to clip from the Input raster drop down list. Select the file (raster or vector) that represents the boundaries of the area from the feature mask data drop down list. Name the Output Raster. Click OK.

34 Resulting fuel model layer, clipped to a fire boundary. Converting Between Integer and Float Rasters Converting between Integer and Float rasters is easily achieved through the Int geoprocessing tool within ArcToolbox. Open ArcToolbox if not already open.

35 Navigate to: Spatial Analyst Tools Math Select: Int Alternatively, within ArcToolbox, select the Index tab. Then type int in the keyword search box. Select: Int (sa)

36 When the tool opens, select the float raster from the drop down list. Name the output raster (with no output extension; see raster file types discussion), then click OK. Seaming Together two or More Pieces of Raster Data (Mosaic) Open ArcToolbox if not already open.

37 Navigate to: Data Management Raster Raster Dataset Select: Mosaic to New Raster Alternatively, within ArcToolbox, select the Index tab. Then type mosaic in the keyword search box. Select: Mosaic to New Raster.

38 Select the raster data sets you would like to seam together from the drop down list or navigate to them using the open folder. Choose an output location and the cell size that is common to all of your data. NOTE: In this scenario the optional fields can be left as is. The coordinate system and cell size should all be the same, because you have already ensured that everything you are working with is in the same projection and has the same cell size (see previous section). Leave the Pixel type Bands and colormap modes as their default values. The mosaic method field is chosen if there is overlap between the datasets. This determines which dataset will overwrite the other, the first one in the list or the last. Ensuring that Zero is the NoData Value & Making Zero the NoData Value In order for the Modify Raster Values, Apply to Selected (Non Zero) Pixels in layer process to work properly, zero (or a negative number) must be the NoData value. If zero or a negative number is not the NoData value, ArcFuels will perform your change globally, rather than to the areas encompassed by a specific layer.

39 In ArcMap or ArcCatalog, right-click on a raster data set and select Properties. Under the Source tab, scroll down to determine the NoData Value. In this example, 255 is the NoData Value. The Modify Raster Values tool will not work with the NoData Value set to 255. To change this, Open ArcToolbox, if not already open.

40 Navigate to Data Management tools Raster Raster Dataset. Select Copy Raster. Alternatively, within ArcToolbox, select the Index tab. Then type Copy in the keyword search box. Select: Copy Raster (management).

41 When the tool opens up, select the raster you want to copy from the Input Raster drop down list. Name the output file, being careful to DELETE the.img from the name. Enter 0 as the NoData Value. Click OK. Zero should now be the NoData value in your newly copied raster.

42 Spatial Analyst Activate the Spatial Analyst toolbar and set up your options. Select Spatial Analyst Options. There are three tabs to review in the window that pops up: General, Extent, and Cell Size. General Tab Working Directory establishes the location where your outputs will be saved. Analysis Mask identifies those locations within the analysis extent (see Extent tab below) that will be included when performing an operation or function within Spatial Analyst. The mask can be a raster or a feature class. For rasters, all input cells that fall outside the mask will not be considered in the analysis and will be assigned the NoData value in the result. For example, you could use an analysis mask to clip rasters to your study area or to change a fuel model within a desired area. Analysis Coordinate System gives you the ability to re-project your outputs to the projection of the data frame while processing data. If you want to use this feature, pick the lower radio button option. The General Tab in Spatial Analyst Options Establish your working directory, an analysis mask, and output coordinate system. Extent Tab

43 Analysis Extent establishes an area or subset of a larger dataset that will be included when performing an operation or function within Spatial Analyst. All subsequent output rasters from an analysis will be sized to this extent. Note that if you select your analysis mask or one of the rasters in your table of contents as the analysis extent, you do not need to worry about the Snap to Extent. ArcMap will automatically snap your data to the analysis extent. Analysis Extent Snap extent to If you do not select an Analysis extent, you need to select one of your data sources in your table of contents to ensure that the cells of the outputs line up with the inputs. See the graphic below for a visual depiction of the snapping. See the Converting Polygons to Raster section of this Part 6: GIS Tips and Tricks to learn how to align (snap) data if they are not already aligned. Unaligned (left graphic) and Aligned (right graphic) input (black) and output (blue) raster data.

44 The Extent Tab in Spatial Analyst Options If you select a raster in your table of contents, you do not need to select Snap to Extent. ArcMap will automatically snap your data to the analysis extent. The Extent Tab in Spatial Analyst Options If you do not select an Analysis extent, you need to select one of the rasters in your table of contents to ensure that the cells of the outputs line up with the inputs. Cell Size To ensure your output cell size is the same as your input, select one of the rasters in your table of contents from the drop-down list or specify a desired cell size. See the Cell Size section of this Part 6: GIS Tips and Tricks to review the importance of cell size and how to modify cell size. Once your options are set, you are ready to use the features within Spatial Analyst. You need to check and re-set these options after every time you process data using Spatial Analyst. The options will return to their default settings after every operation or function.

45 Creating a New Raster Using the Raster Calculator within Spatial Analyst Set you Spatial Analyst options as described above. In this example, we will be creating a new raster with the Mt. Emily demonstration data containing slopes < 30%. Under the General tab our working directory is: C:\arcfuels\data. We do not need an analysis mask. Under the Extent tab, select the slope raster (or the fuel model raster, as all rasters in the demonstration data all have the same extent) as the Analysis extent. Under the Cell Size tab, select Same as Layer slope (or Same as Layer fml, as all rasters in the demonstration data all have the same cell size). Activate the Spatial Analyst toolbar and select Spatial Analyst Options. Select your working directory (c:\arcfuels\data). Select your Analysis Extent (Same as Layer slope ).

46 Select Cell Size (Same as Layer slope ). See the previous section for more detail related to Spatial Analyst options. Open the Raster Calculator by selecting Spatial Analyst Raster Calculator. The syntax for the raster calculator is as follows: o o [raster you are creating] = [raster calculation is based on] OR raster you are creating = [raster calculation is based on] The first option creates a temporary raster, while the second option creates a permanent raster. It is important to know whether your slope raster is in degrees or percent. As a rule of thumb, if you have slope values >100, your raster is percent, since values of slope in degrees over 90 would be infinite. The demonstration data contain values over 100 and are therefore in percent. See the Slope Degree to Slope Percent Conversion table in Part 5: General Help for a slope degree/percent conversion table. Type the following in the Raster Calculator box and then click evaluate: [new raster] = [slope] <30 This will create a new temporary raster of ones and zeros where the ones represent the area where slope < 30%.

47 Raster Calculator set-up to create a new temporary raster of 1s and 0s where 1s represent the area of ground where, slope < 30%. New temporary raster of 1s and 0s where 1s represent the area of ground where, slope < 30%.

48 Now, get rid of those 0s. Note that you do not have to get rid of the 0s in order to use the processes demonstrated in Module 1-1. However, this is an important process to learn. If not open already, Open ArcToolbox Extract by Attributes. and navigate to Spatial Analyst Tools Extraction When the window opens, select new_raster as the input raster and name/save the output raster to a desired location. A good name for this raster is slope30. In this scenario, we are saving to our c:\arcfuels\data folder. Under the Where clause, click the SQL button, and enter VALUE > 0. This can be done by double-clicking on the word VALUE in the top box of the SQL window and using the Get Unique Values and mathematical operators (e.g., >, <, like) buttons or by typing in the expression manually, with the quotation marks. You can verify that your expression is valid by clicking the Verify button. Click OK after your expression is verified to exit the query builder, then click OK again to launch the extraction process. In your resulting raster, 0s have been replaced with NoData values. Verify this using the Identify button. Open ArcToolbox if not already open.

49 Navigate to: Spatial Analyst Tools Extraction Extract by Attributes Extract by Attributes tool showing new_raster as the Input Raster and slope30 as the Output Raster Click the SQL button under the Where clause to build an expression that will extract the 1s from new_raster.

50 Query builder that results from selecting the SQL button under the Extract by Attributes tool. Manually type in the phase VALUE > 0 exactly as shown or use the buttons within the tool. Verify your expression by clicking the Verify button. Click OK after your expression is verified. Resulting slope30 raster where 1s represent slopes < 30%. The 0s have been replaced with NoData.

51 Verify this by using the Identify button. Now, with your newly created slope30 raster, you can modify the fuel model layer using the Modify Raster Values button and the process outlined in Exercise Building a Difference Raster Using the Raster Calculator Set up your Spatial Analyst Options as shown in previous section of this Part 6: GIS Tips and Tricks. Open the Raster Calculator from the Spatial Analyst drop-down list. Subtract your post treatment raster from your pre-treatment raster. Use your reclassified (i.e., flame length broken into hauling categories) or unclassified data. In this example, post treatment flame length is subtracted from pre-treatment flame length.

52 View the properties of your newly created raster (right click properties). Select Unique Values. Notice the pixel count of each value. Positive numbers represent a reduction in flame length; negative numbers represent an increase in flame length. Group these values into categories that are meaningful to you by selecting the values (hold down the control key to select more than one) right click Group Values. Label each grouping.

53 In this example, flame length increases are shown in red; flame length decreases are shown in blue; black pixels are areas of no change. Note that since flame length is produced from a static run, there should be no change from pre- to post-treatment outside of the treated units. Repeat with burn probability and other metrics of interest. Summarizing Data 2 As discussed in Module 1-6, you will likely want to summarize and calculate acres of each FlamMap output within your planning area/units/values at risk. Reclassify This is accomplished using the Reclassify tool in ArcToolbox or the Reclassify tool in Spatial Analyst. Note that both tools result in the same output. Use the Spatial Analyst tool if you want to reclassify only a portion of your data. Note that if you use the Spatial Analyst tool, you will need to set up your Options appropriately. See the Spatial Analyst section of this Part 6: GIS Tips and Tricks for more detail. 2 Chris Zanger, The Nature Conservancy, czanger@tnc.org contributed to the Summarizing Data sections.

54 Open ArcToolbox if not already open. Navigate to: Spatial Analyst Tools Reclass Reclassify

55 Select from the drop down list or navigate to the raster you want to reclassify. Choose Value (in this scenario, value = flame length) from the Reclass field drop down list. Click Classify. Under Classification Method select any method that will allow you to change the number of Classes. If classifying flame length into hauling categories, you will want 4 categories. Set 4, 8, and 11 as the first three Break Values. Leave the highest break value as is. This will result in 4 categories of rounded flame length, 0-4, 4.1-8, , and ft. If you have a large area of No Data or unburnable fuels in your modeling area, consider adding 0 as a category by using the Exclusion button. Click OK.

56 Enter the upper limit of each hauling category into the New Values column, name the Output Raster and click OK. NOTE: This same technique works to Reclassify integer or float data. NOTE: Consider using five categories if you have a significant amount of non-burnable fuels within your landscape. Reclassify the zeros into their own category, so it does not appear that rocks or water have a flame length of up to 4 ft. Combine After all of your data have been Reclassified into categories that are appropriate for summarization and your treatment units are in raster format, you are ready to use the Combine tool. A combine can also be executed with the Raster Calculator within Spatial Analyst. Open ArcToolbox if not already open.

57 Navigate to Spatial Analyst Tools Local Combine. In this example, flame length, crown fire, and treatment locations will be combined. Use the drop down list or navigate to the rasters you want to combine. Name the output raster and click OK.

58 This output shows the number of times (Count) each combination of the values from the combined raster (treat_loc, cf_notrt, fl_notrt_re) occurs. For example, there are 299 pixels within treatment unit 652 where crown fire = 1 and flame length = 4. In this output, the Value field has no relevance to the data. Next step is to add a field and calculate acres. Summarizing Data: Calculate Acres From the Options menu, select Add Field.

59 Name the field Acres and Select Type Float. Leave the precision and scale as 0. Right click on the newly created Acres column and Select Field Calculator. Select Yes to the warning that pops up.

60 You are going to calculate acres based on your knowledge of your data s cell size. In the demonstration data, each pixel (cell) is 30m x 30 m or 900 m 2. Open a web browser to Google. Type convert 900 meters squared to acres. The following conversion will appear. 900 (meters squared) = acres If you are using rasters with a 25 m (or any other) cell size you will need to type convert 625 meters squared to acres in the Google search engine. Double-click on Count in the Field list box. It will appear in brackets below. The Count field is the number of 30 m X 30 m (or 900 m2) cells. Multiply the Count field by the conversion factor and click OK.

61 Open the attribute table of the combined raster. The Acres field is now populated. Export this table to Excel (Options Export). Summarize the data by plot (treat_loc in this example) using a pivot table. Zonal Statistics Zonal Statistics are used to summarize your data based on zone data. The output can be a table or a new raster. Zone data are any areas within which you would like to summarize your data. In other words, if you want to summarize the flame length within your treatment units (zones) use zonal statistics. Zonal Statistics can also be used to pick the value within a zone which represents the majority, as described in Module 1-7. If you want to summarize multiple layers across a zone, use the methods described in Module 1-6. Open ArcToolbox if not already open.

62 Navigate to Spatial Analyst Tools Zonal. Select Zonal Statistics as Table.

63 When the tool opens, select the zone data (i.e., treatment units). This can be a raster or vector data layer. The zone field is the attribute within the zone data layer you would like to summarize across (i.e., treatment units). In the treat_loc file value = treatment units. The Input Value Raster is the raster you would like to summarize. In this example, this is pre-treatment, unclassified flame length. Place a check mark next to Ignore NoData. Navigate to a saving location and name the output table. Click OK.

64 Select the Source tab to view your table in ArcMap. Right-click on the zonal table and select, Open. Alternatively, navigate to where you saved your table and open it through Microsoft Excel. It will have a.dbf extension.

65 Examine the table. Value represents treatment unit. In this example, Unit 652 has a minimum of 3, maximum of 65 and average of 22 ft flame lengths. Navigate to Spatial Analyst Tools Zonal Select Zonal Statistics.

66 When the tool opens, select the zone data (i.e., treatment units). This can be a raster or vector data layer. The zone field is the attribute within the zone data layer you would like to summarize across (i.e., treatment units). In the treat_loc file, value = treatment units. The Input value raster is the raster you would like to summarize. In this example, haz_units = hazard within treatment units. The Statistics type in this example, majority creates a new raster which identifies each unit based on the majority of hazard pixels. Navigate to a saving location and name the output table. Click OK. The resulting raster will look odd. As with any ArcMap raster process, only the VALUE field is carried over. In this example, the Value field is the haz_unit raster. You will need to Join the resulting raster back to the original hazard units raster to display the hazard classifications. Continue to the next section for instructions related to this process.

67 Post-Processing: Joining Attribute Tables of Raster Data Often, the output from ArcMap raster processes contains only a Value field. This Value field is the link back to the original data source and the associated attribute table. To re-attach the attribute table associated with the output, it needs to be Joined back to the original data source. This example continues from the previous section on Zonal Statistics. Right-click on the raster which needs to be Joined back to the original data source. Select Joins and Relates and then Join.

68 From the drop down list, select Join attributes from a table : 1. The field the Join will be based on is the Value field, 2. The table to Join to this layer is haz_unit, as this is where the Value field originated from, and 3. Base the Join on the Value, as this is the field which is common to the output and the original data. Keep only the matching records, since the original data set contained more information (rows of data) than the output. Click OK. Use the Symbology tab within the Layer Properties to verify that the join was successful.

69 Summarized data Joined to original data (left). Original data (right). To make the join permanent, right-click on the layer. Select Data and then Export Data.

70 Verify the cell size. Navigate to an output folder. Rename the file (erase the.img extension). Select Raster from the Format drop down list. Click Save. Exporting ArcGIS Data to Google Earth If you want to share ArcGIS spatial data for public viewing in Google Earth there is an ArcToolbox tool that will generate KML (keyhole markup language) files from ArcGIS layers. The files can then be distributed or posted at a Google Earth site for viewing in Google Earth. Open ArcToolbox if not already open.

71 Navigate to Conversion Tools To KML Layer To KML. Select your layer to be converted from the drop down list. Navigate to an output location and name the file. ArcMap creates a KMZ rather than a KML, which is just a compressed KML file. There is no need to decompress it. Choose a reasonably large layer output scale. This determines the scale at which you can see your file in Google Earth Click Ok.

72 In windows explorer, doubleclick on your KMZ file. This will automatically open Google Earth. These are the flow paths from the demonstration data. Alternatively, navigate to your KMZ, by selecting File Open.